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DPChallenge Forums >> Hardware and Software >> Canon 70-200 f/4 L lens - Sharpness?
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 04/09/2005 10:17:42 PM · #1
I have taken a few pictures with my new lens but the sharpness seems to be disappointing to me on long range shots. I have read the pamphlet that came with the lens and the manual to the camera. I have a new camera, exchanged today, and it IMO is doing the same. Could you please look at these photographs and let me know if they look sharp or if they look as if the lens is not doing its job. Could be my fault I'm still trying different settings. All photographs have had USM added @ 100.2.1.

04/09/2005 10:27:46 PM · #2
They do not look terribly unsharp, but it's impossible tojudge sharpness from 640px images, unless they are 100% crops out of the originals. Here's what I'd do:
- Find a distant subject that is relatively flat and has high-contrast detail (a brick building in sunlight will do nicely).
- camera on tripod, focus carefully, shoot. If testing AF, use center focus point, otherwise focus manually.
- Shoot wide open and at f/8
- Crop out a 640x640 area of the pics to post, identifying the focus point. Post the (resized) original for reference

The above procedure should help identify if there is a problem. If focus problems are suspected, then shooting a subject like above but at an angle, will help gretly, since you should see how the n-focus area relates to the (known) focus point.

Edited for typos, LOL

Message edited by author 2005-04-09 22:28:27.
 04/09/2005 10:29:33 PM · #3
It's hard to tell from these reduced images (any softness could be result of the reduction itself), but they look like they could be OK. Try posting a 100% crop of a detail area in one.

This shot was taken handheld and fully extended with the same lens a day after I got it.


Looks like Kirbic beamed a post in while I was taking a shuttle. ;-)

Message edited by author 2005-04-09 22:32:09.
 04/09/2005 10:36:13 PM · #4
Scott, they look pretty good to me. You can always do a test against your other lenses in your home studio environment (though you'll need to back up a bit more with the 70-200 ;)

You should try posting 100% crops instead of reduced images. It's hard to see anything in a reduced image.

There are some sharpness tests--"charts" you can photograph--that can be found on the web. I don't have a location right now, but I'll check later if I get a chance.

I did some tests with some flowers comparing my lenses if you search through the forums. This was not as clean as doing one of the charts. But it gave me a good idea that my Sigma was a pretty good lens even compared to my 50mm 1.8.

Just did a quick search... here are some charts:

Chart 1

Chart 2
 04/09/2005 10:37:55 PM · #5
Originally posted by scalvert:
...while I was taking a shuttle. ;-)


Is that a euphemism? ;-)
 04/09/2005 10:38:03 PM · #6
Originally posted by kirbic:
They do not look terribly unsharp, but it's impossible tojudge sharpness from 640px images, unless they are 100% crops out of the originals. Here's what I'd do:
- Find a distant subject that is relatively flat and has high-contrast detail (a brick building in sunlight will do nicely).
- camera on tripod, focus carefully, shoot. If testing AF, use center focus point, otherwise focus manually.
- Shoot wide open and at f/8
- Crop out a 640x640 area of the pics to post, identifying the focus point. Post the (resized) original for reference

The above procedure should help identify if there is a problem. If focus problems are suspected, then shooting a subject like above but at an angle, will help gretly, since you should see how the n-focus area relates to the (known) focus point.

Edited for typos, LOL


Thanks Kirbic. I will try that tomorrow and post in this thread a 100% crop. Right now I have been shooting in AF. I'm sorry if I sound stupid about this but I'm new with a dslr. When I look through the view finder I have a center focus point then 2 to the left, 2 to the right, 2 to the top, and 2 to the bottom. I guess thats a 9 point AF. Should I be shooting a different way?

Here is a 100% crop of one of the images today with no usm added. Also shot handheld.
04/09/2005 10:40:02 PM · #7
The building just seems to be snaping into focus at the far left edge of the 100% crop. There's not a lot of contrast, so it becomes a bit hard to judge. I assume this was taken wide open?
 04/09/2005 10:40:15 PM · #8
Originally posted by kirbic:
Originally posted by scalvert:
...while I was taking a shuttle. ;-)


Is that a euphemism? ;-)


Well I guess I was on a Rigelian freighter; when I started answering, there were no responses. ;)
 04/09/2005 10:46:31 PM · #9
Originally posted by kirbic:
The building just seems to be snaping into focus at the far left edge of the 100% crop. There's not a lot of contrast, so it becomes a bit hard to judge. I assume this was taken wide open?



EXIF DATA
04/09/2005 10:47:20 PM · #10
just post a picture in a challenge. The out of focus and unsharp specialist commentors will let you immediately.
 04/09/2005 10:50:19 PM · #11
Originally posted by nshapiro:
Scott, they look pretty good to me. You can always do a test against your other lenses in your home studio environment (though you'll need to back up a bit more with the 70-200 ;)

You should try posting 100% crops instead of reduced images. It's hard to see anything in a reduced image.

There are some sharpness tests--"charts" you can photograph--that can be found on the web. I don't have a location right now, but I'll check later if I get a chance.

I did some tests with some flowers comparing my lenses if you search through the forums. This was not as clean as doing one of the charts. But it gave me a good idea that my Sigma was a pretty good lens even compared to my 50mm 1.8.

Just did a quick search... here are some charts:

Chart 1

Chart 2


Thank you for the links.
 04/09/2005 10:52:13 PM · #12
To know for sure take a few photos with the camera on a tripod and using a remote release or timer release. Most of the time sharpness issues are due to shake.
 04/09/2005 10:53:45 PM · #13
Ah, f/5.6... 1/320... 70mm. Well, camera shake should have not been an issue, though identifying what the camera focused on is. When yo do a lens test, set the camera to use only the center point of the nine you see in the viewfinder. That way you are certain what the camera selected as the focus point.
Looking carefully again at the 100% crop, it looks fairly sharp, maybe not quite as sharp as I'd expect, but given the low-contrast subject, it might just be as good as it can get.

Message edited by author 2005-04-09 22:55:20.
 04/09/2005 10:56:04 PM · #14
One of the best compairisons of lens sharpnesses is a brick wall. Very often used.
 04/09/2005 10:58:12 PM · #15
Thanks everyone. I just thought this L lens would render better results than what I'm getting. Like I said it is more than likely an issue with me and not the lens. I'm going to print out a chart and and take a test shot and see what happens. I'm going to try to do that tonight if I can.
 04/09/2005 11:17:37 PM · #16
The first pics look sharper than anything my Canon 75mm - 300mm (non-L lens) has ever taken. For what its worth.
 04/10/2005 12:10:53 AM · #17
Originally posted by kyebosh:
One of the best compairisons of lens sharpnesses is a brick wall. Very often used.


Ok, how far away should I stand before throwing the lens? ;)
 04/10/2005 12:19:30 AM · #18
Thanks for all the help everyone. I hope I'm not being to much of a bother. I just want to make sure everything looks OK and get as much out of my equipment as possible. Purchasing this equipment was a hard decision but when I made the decision it was happy one. I know I have had a lot of questions and I apologize but this is a big learning curve for me.
I just want to thank you for commenting
kirbic
scalvert
nshapiro
eaglebeck
doctornick
kyebosh
and
bbower1956

Thank you all
Scott W.
 04/11/2005 02:17:28 AM · #19
Follow up post. I believe I have the sharpness problem fixed. Does this look sharp for the L lens?
NOTE: Sorry for deleting the other photographs to compare by.
- Original resized to 640x427
- 100% Crop

Message edited by author 2005-04-11 02:24:42.
 04/11/2005 04:21:19 AM · #20
It's no good posting a 100% crop of a part of the image that's out of focus.

You're asking the wrong questions. Sharpness is but one reason to buy this lens, and it isn't the first. A telephoto lens has different characeristics than a normal or wide-angle lens. I have this lens too. Contrast, constant aperture, build quality, resistance to flare, constant length, focusing speed, lack of distortion, USM, etc. are as much a reason to lay down the cash as mere sharpness, which is good if you recognise that you're not going to get tack sharp photos as easily with a telephoto. I usually shoot this lens at ISO 400 for just this reason, even in bright sunlight.

Take into account the focusing mechanisms of the consumer bodies, too. On a 1D it may snap accurately into focus such that the focus is always good even at f/4, but on my 10D at least this isn't the case. Shoot stopped down a bit for a comparison.

The real potential for sharpness isn't going to be recognised with this lens unless it's on a good tripod. In everyday shooting I get as much pleasure out of the lovely colour and contrast this lens produces as its sharpness. It and my 17-40 often need no contrast adjustment at all, which is something I can't say about every lens I own.

Shoot something at f/16 off a tripod and you'll see how well this thing does in ideal conditions.


04/11/2005 06:00:54 AM · #21
Originally posted by nshapiro:
Originally posted by kyebosh:
One of the best compairisons of lens sharpnesses is a brick wall. Very often used.


Ok, how far away should I stand before throwing the lens? ;)

It depends on brand, but extensive tests have proven that with L Glass you can stand both much closer and much further away from the wall, they really are that much better than the competition. Inferior brands have been known to fall apart before they even reached the wall or in some cases have failed to reach the wall at all, even from extremely short distances.

:D

Can't say anything about the sharpness of the lens because as Jimmy points out, the crop is a part of the image that's out of focus and all the other links are dead :-/
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